Every holiday season, the indoor rooms of local Armstrong’s Garden Centers are carpeted in poinsettias. Besides the traditional Santa suit red, there are now cultivars colored to compliment every decor. Lemon yellow, mauve and maroon; the flower-like bracts come dressed in solids and charming permutations of splotched and splattered colors to please more playful palettes.
In weeks to come, the dominant colors will fade from glory. The moment of decision at hand: to keep or to toss. Commercial growers of poinsettia (Euphorbia pulcherrima) take extraordinary steps to manipulate specific conditions to present plants at their peak of perfection during holiday party season.
If you aren’t interested in building a greenhouse equipped with the grow lights, movable blackout shade cloths, and temperature control equipment required to manipulate the growth cycle throughout the year, then seasonal beauty can be had with poinsettia plants grown outdoors. However, be aware in nature, the peak season is not the Christmas season.
Growing up in Whittier, I remember the poinsettia my mother grew. It matured into a leggy tree, not quite tall enough to touch the single story ranch home's eaves. It came into bloom closer to a date we now associate with Martin Luther King, Jr. Day: mid-January.
To grow outdoors in Diamond Bar, the key to success is location, location, location. Scout your garden to find a sheltered spot where winds will not wickedly whip the tender perennial; where a rare frost event won’t bite off life from its limbs. Amend the native clay soil so that needed moisture drains away before the Christmas plant dies from drowning. Make certain there is no porch light that could disrupt the winter darkness poinsettias require to develop what the plant is revered for: vivacious color.
If you are of the obsessive nature needed to force a poinsettia to rebloom in December and cannot go the greenhouse route, choose an outdoor sunny spot where you will remember to give your prize plant a drink whenever the soil dries out. To allow excessive water to drain off, keep the plant potted up above a gravel filled saucer. Don’t panic when the leaves drop. This is your signal to cut back the stems to six inches tall, being sure to leave on each limb at least two nubs. Newer gardeners will find this next point counter-intuitive. However, trust me. Pinching back new growth every few weeks over the course of the year paints lushness over otherwise naked stems.
Now, the reason a poinsettia is kept in a pot instead of planting for December bloom is the longer nights of winter must be replicated. Sometime between just after the start of the school year and Columbus Day, every night the potted plant needs to be moved to a dark spot, an unlighted closet, shed or garage for 14 hours. Which is to say, the precious pot takes daylight beginning at breakfast then turned in after dinner.
If you can keep up this diet of limiting sunshine to 10 hours a day for eight to 10 weeks during the specified period, you may be on an aspirin regimen for all that lifting, but you should be rewarded with vivid holiday color.